From patchwork Fri Dec 22 09:44:57 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [4/8] xfrm: Fix stack-out-of-bounds read on socket policy lookup. X-Patchwork-Submitter: Steffen Klassert X-Patchwork-Id: 852277 X-Patchwork-Delegate: davem@davemloft.net Message-Id: <20171222094501.23345-5-steffen.klassert@secunet.com> To: David Miller Cc: Herbert Xu , Steffen Klassert , Date: Fri, 22 Dec 2017 10:44:57 +0100 From: Steffen Klassert List-Id: When we do tunnel or beet mode, we pass saddr and daddr from the template to xfrm_state_find(), this is ok. On transport mode, we pass the addresses from the flowi, assuming that the IP addresses (and address family) don't change during transformation. This assumption is wrong in the IPv4 mapped IPv6 case, packet is IPv4 and template is IPv6. Fix this by catching address family missmatches of the policy and the flow already before we do the lookup. Reported-by: syzbot Signed-off-by: Steffen Klassert --- net/xfrm/xfrm_policy.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c index 9542975eb2f9..038ec68f6901 100644 --- a/net/xfrm/xfrm_policy.c +++ b/net/xfrm/xfrm_policy.c @@ -1168,9 +1168,15 @@ static struct xfrm_policy *xfrm_sk_policy_lookup(const struct sock *sk, int dir, again: pol = rcu_dereference(sk->sk_policy[dir]); if (pol != NULL) { - bool match = xfrm_selector_match(&pol->selector, fl, family); + bool match; int err = 0; + if (pol->family != family) { + pol = NULL; + goto out; + } + + match = xfrm_selector_match(&pol->selector, fl, family); if (match) { if ((sk->sk_mark & pol->mark.m) != pol->mark.v) { pol = NULL;